A WebExtension can request access to local files without the warning prompt stating that the extension will "Access your data for all websites" being displayed to the user. This allows extensions to run content scripts in local pages without permission warnings when a local file is opened. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.
http://www.securityfocus.com/bid/105718
http://www.securitytracker.com/id/1041944
https://access.redhat.com/errata/RHSA-2018:3005
https://access.redhat.com/errata/RHSA-2018:3006
https://bugzilla.mozilla.org/show_bug.cgi?id=1487478
https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
https://security.gentoo.org/glsa/201811-04
https://usn.ubuntu.com/3801-1/
https://www.debian.org/security/2018/dsa-4324
Source: MITRE
Published: 2019-02-28
Updated: 2019-03-01
Type: CWE-200
Base Score: 3.6
Vector: AV:L/AC:L/Au:N/C:P/I:P/A:N
Impact Score: 4.9
Exploitability Score: 3.9
Severity: LOW
Base Score: 7.1
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Impact Score: 5.2
Exploitability Score: 1.8
Severity: HIGH